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Photooxidation of polypropylene under natural and accelerated weathering conditions
Author(s) -
Tidjani Adams
Publication year - 1997
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19970627)64:13<2497::aid-app3>3.0.co;2-8
Subject(s) - polypropylene , crystallinity , elongation , photodegradation , polymer chemistry , radical , decomposition , materials science , derivatization , gel permeation chromatography , reaction mechanism , chemistry , polymer , chemical engineering , ultimate tensile strength , organic chemistry , composite material , chromatography , catalysis , mass spectrometry , photocatalysis , engineering
The environmental and accelerated photodegradation of two polypropylene (PP) films (high and low crystallinity) were investigated. FT‐IR measurements coupled with derivatization reactions (NO and SF 4 ), elongation at break tests and gel permeation chromatography technique were used to monitor the degree of oxidation during the UV exposure. No stoichiometry changes were observed under both UV conditions for the PP films. The dominant photoproduct, i.e., ketone, was suggested to be produced from peroxy radicals. The low concentration of tert‐alcohol detected questioned the validity of its formation from hydroperoxide decomposition as suggested by several authors. Under natural exposure, the effect of degradation on mechanical property was different for high and low PP. High PP was useless after a short exposure time; low PP retained its physical property for a longer period of time. In the latter case, the analysis of the changes in elongation at break, the polydispersity P = M w / M n , the number of chain scissions N t , and the kinetic accumulation of photoproducts provided strong indications on the mechanisms of acid and ester production and shed some light on the competition between crosslinking and chain scission reactions. The estimated acceleration factors were 7.5 and 8.5 for high and low PP, respectively, values that were much lower than those obtained for linear low‐density polyethylene. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2497–2503, 1997